An unhealthy microbiome might even play a role in the fact that people with IBS are more prone to certain psychological problems such as stress, which in turn seems to further exacerbate their IBS symptoms.

A recent study that transplanted the microbiota of humans with IBS into mice found that the mice showed not only physical symptoms associated with IBS, such as faster transit of food through the gut and an altered immune response, but behavioural ones too, such as anxiety.